Geo selective sync API support

The following discussion from !4286 (merged) should be addressed:

  • @nick.thomas started a discussion:

    On the subject, it seems a little odd that you can't see or manage selective sync settings in the main Geo API. I'll create a follow-up issue for that.

The GeoNode entity and Geo API needs support adding for:

  • selective_sync_type
  • selective_sync_shards
  • namespace_ids (probably best named selective_sync_namespace_ids for clarity and consistency)
Edited by Toon Claes